What can they do other than require max vaccination and hope there’s no carriers in the tour group? Quarantine them for 10-14 days on entry, as no vaccine prev

What can they do other than require max vaccination and hope there’s no carriers in the tour group? Quarantine them for 10-14 days on entry, as no vaccine prevents transmission? And there’s enough of a lag for the tests to work that it can’t pick up a hot traveller who has been recently infected. Maybe force quarantine before departure to offload the expense?